Party speak

Should the next Speaker of the House of Commons be a Labour MP on the basis that John Bercow was a Conservative before taking the chair? There has been a tradition in recent decades that the two main parties alternate in filling the role. But it doesn’t go back far — Michael Martin, Labour MP for Glasgow Springburn, succeeded Betty Boothroyd, also Labour, in 2000, not least because the Conservatives had only 165 MPs at the time and didn’t want to lose one.